As shown in FIG. 5, a conventional microwave stripline resonator consists of a strip electrode 6B provided on a surface of dielectric substrate 1 and a grounding electrode 3 provided on adjacent surfaces of dielectric substrate 1. The strip electrode and the grounding electrode are interconnected.
With such a construction of conventional resonator, the length of strip electrode 6B is exclusively determined by its resonant frequency. Therefore, the employment of dielectric substrate 1 having a large dielectric constant is desirable to make the resonator more compact.
However, a dielectric substrate having a large dielectric constant is generally associated with a lower no-load Q and an irregular flatness of temperature coefficient characteristics. Thus, a dielectric substrate having a large dielectric constant exhibits poor resonator characteristics.